Conventionally, there is a method for manufacturing a polyester textured yarn which creates a heather-like appearance when it is subjected to a dyeing operation (Japanese patent laid-open No. 61758/73). In this method, a polyester multifilament yarn which is dyeable with ionic dyes is mixed with a polyester multifilament yarn which is not dyeable with ionic dyes, and then, the mixed yarns are subjected to an interlacing treatment in a turbulent fluid flow, and thereafter, the interlaced yarns are false twisted. Although the textured yarn obtained through the above-mentioned method has a heather-like appearance, it has a disadvantage in that it does not have a hand similar to that created by a spun textured yarn.
German patent application P2902949 discloses a method wherein multifilament yarns having different breaking elongations are used so that the multifilament yarn with a smaller breaking elongation constitutes the core portion and the multifilament yarn with a larger breaking elongation constitutes the wrapper position. Accordingly, the spun-like effect of the obtained yarn is increased. However, if such a yarn is dyed, the color tone of the core portion is conspicuous, and as a result, there occurs another disadvantage in that the yarn has an inferior heather-like appearance.
In conclusion, at present, there is no textured polyester yarn having both a good heather-like appearance and a spun-like effect, and therefore, the development of such a textured yarn has been desired in this field.